750 THE JOURNAL OF GEOLOGY. 
The reports of the Missouri River Commission show, in pro- 
file, the results of a series of test borings across the entire 
breadth of the valley at Sibley, Missouri.*. The rock floor 
nowhere stands more than sixty-five feet below low water, or 
little, if any, below the scour of the present stream. Borings at 
St. Charles, Missouri, on the very border of the Mississippi Val- 
ley, apparently test the rock floor of the Missouri in its lowest 
part, and find it but seventy feet below low water.? Only twenty 
miles below St. Charles at Bellefontaine, the bridge shows at its 
north pier a rock floor 107 feet below low water at this point. 
The rock floor is perhaps still lower between there and the Mis- 
sissippi channel four miles to the north, there being a slight 
northward descent in the rock floor at the north pier. The 
available data seem to indicate that where the Missouri joins the 
Mississippi, the latter has a channel forty to fifty feet or more 
deeper than the former. 
ALTITUDES OF THE ROCK FLOOR AND PRESENT MISSOURI AT BRIDGES 
BETWEEN SIOUX CITY, IOWA, AND THE MOUTH OF THE STREAM." 
Location Dist. Miles Low water secu s Becks Bee 
Ft. In. Ft. 
Sioux City, lowa............. fo) 1076 950 + 
Blair, Nebraska.............. 102.8 986 10.50 934-944 
Omaha, Nebraska............ 35-5 963 7-77 839-890 
Plattsmouth, Nebraska........ 25.5 943 9.41 872 
Nebraska City, Nebraska...... 25.9 gIo 15.29 7502 
eee | 
Rulo, Nebraska,.............. 70.2 843 11.45 7153 
White Cloud, Kansas......... 12.1 833 9.90 772 
St. Joseph, Missouri........... 46.4 794+ 10.08 743 
Leavenworth, Kansas......... 57.2 745 10.28 688 — 
Kansas City, Missouri......... 31.1 721 9.26 660-680 
Randolph Bluffs, Missouri..... 4.0 713 24.00 631 
Sibley, Missouri........ ..... 30.7 690 7.52 625-655 
Glasgow, Missouri............ 102.5 594 10.23 550 
Booneville, Missouri.......... 31.7 570 9.08 513 
St. Charles, Missouri.......... eyo) 420 10.13 350 
Bellefontaine, Missouri........ 21.7 406 } 7.79 205 
402 J 
* Report of Missouri River Commission for 1889-90, Appendix XX. of the Annual 
Report of the Chief of Engineers for 1890, p. 3379, Plates V. and VI., Government 
Printing Office, Washington. 
2 Loc. cit., p. 3377 and Plates I. and II. 
